I. Field of the Invention
The present invention relates to an epoxy resin-based composition and, more particularly, to an epoxy resin-based composition which has good stability in storage at normal temperatures and which rapidly cures at elevated temperatures to have various excellent characteristics.
II. Description of the Prior Art
Epoxy resins, when cured, may exhibit various favorable physical characteristics such as good adhesiveness, as well as good mechanical, electrical and thermal characteristics. Generally, agents for curing epoxy resins may include a hardner such as polyamines, acid anhydrides, phenols or the like, and a curing catalyst such as boron trifluoride (BF.sub.3) complexes, tertiary amines or the like.
Polyamines may react strongly with the epoxy resin, so that resins containing them may not be stored for long periods of time. Acid anhydrides and phenols may require high temperatures and heating for a long period of time to cure the epoxy resin. Although BF.sub.3 complexes may cure the epoxy resin at relatively low temperatures, the resulting cured resin has inadequate electrical and mechanical characteristics at high temperatures. Tertiary amines requires high temperatures to cure the resin and may cause reshes on human skin.
It has recently been proposed that a metal chelate compound be employed as a latent curing agent for epoxy resins. Chelate compounds, however, must be used in a relatively large amount and require temperatures as high as 200.degree. C. or higher for curing epoxy resins, and a necessary catalytic amount of them do not dissolve easily in epoxy resins.
A curing method is also known in which an epoxy resin is subjected to a curing reaction using an organosilicone having a silanol group and an organic boron compound or an organic titanium compound; however, this reaction system cannot provide satisfactory stability in storage, and the resulting cured material has impaired electrical characteristics so that it is not generally practical.